Effects of cinnamon, rosemary and oregano on growth performance, blood biochemistry, liver enzyme activities, excreta microbiota and ileal morphology of Campylobacter jejuni‐challenged broiler chickens

Abstract Background Phytogenic additives would be helpful to mitigate the detrimental impact of Campylobacter jejuni on broiler chickens. Objective The experiment aimed to assess the effects of cinnamon, rosemary and oregano powder on physiological responses of broiler chickens challenged with C. jejuni from 0 to 42 days of age. Methods A total of 192 one‐day‐old male broiler chickens were divided into 6 treatment groups. The treatments included: negative control (NC; basal diet without additives and no C. jejuni challenge), positive control (PC; basal diet with C. jejuni challenge), PC with cinnamon, rosemary or oregano powder (3 g/kg each), and PC with Erythromycin (55 mg/kg). Except for the NC group, all chicks were orally challenged with 2 × 108 CFU/mL C. jejuni daily from days 21–25. Feed intake, body weight gain (BWG), feed conversion ratio (FCR), energy efficiency ratio (EER) and protein efficiency ratio (PER) were assessed during the rearing period (0–42 days). On day 42 of age, fresh excreta samples were collected from each pen to determine apparent dry matter digestibility and excreta microbiota. In addition, at the end of the experiment, blood samples were collected to evaluate blood profile and liver enzyme activities. Results C. jejuni challenge (PC treatment) decreased BWG, EER and PER, while increasing FCR of broiler chickens (p < 0.05), whereas rosemary, oregano and Erythromycin improved these performance parameters akin to NC. PC diet showed negative effect in ileal morphology, alleviated by additives except cinnamon (p < 0.05). Dietary additives successfully reduced Campylobacter levels and increased Lactobacilli counts in the PC. Rosemary and oregano lowered plasma total cholesterol (p < 0.05). Alanine aminotransferase elevation by C. jejuni challenge in the PC group was prevented by rosemary, oregano and Erythromycin (p < 0.05). Conclusions Oregano and rosemary alleviate the impact of C. jejuni challenge.


INTRODUCTION
Feed constitutes a fundamental element in the poultry industry, significantly influencing the gastrointestinal tract and its overall health.
The gastrointestinal tract is recognized as a sophisticated and dynamic organ critical for gut health.Numerous factors, including stressors, can potentially disturb the delicate balance of the gut ecosystem, leading to adverse effects on poultry health and productivity.Gastrointestinal dysbiosis poses significant challenges to the poultry sector by compromising gut health and elevating disease vulnerability.In contrast, a healthy gut in poultry facilitates efficient nutrient digestion and absorption, particularly in environments where these stressors are minimized (Diaz Carrasco et al., 2019).
Campylobacter jejuni, a gram-negative, non-spore-forming bacterium, is a widespread cause of gastroenteritis (Epps et al., 2013;Kaakoush et al., 2015;Moore et al., 2005).It is a significant pathogen responsible for human diarrheal disease.Poultry serves as a significant source of C. jejuni exposure, given that this bacterium thrives within the gastrointestinal tract, posing a major risk for foodborne illnesses in humans worldwide (Beier et al., 2019;Connerton et al., 2018).Its ability to colonize and suppress immune responses in chickens impacts broiler performance (Nooreh et al., 2021).
In the past, antibiotics were employed as growth promoters to combat gastrointestinal pathogens and mitigate the impact of stressors on gut function.Nevertheless, restrictions on antibiotic use in poultry production have been implemented due to rising consumer awareness about antibiotic-related health risks, bacterial resistance and food safety concerns (Ali et al., 2021).In light of the constraints imposed on antibiotic use in chicken production in recent years, the poultry industry has turned to alternative approaches, such as incorporating plant-derived feed additives.The rising interest in plant bioactive compounds, such as phytochemicals, within poultry diets stems from their promising capabilities as antioxidants and antimicrobial agents.As a result, these natural compounds are increasingly sought-after for their potential to support the well-being and health of poultry while aligning with the trend of reducing antibiotic usage (Ali et al., 2021).
Despite some reports on phytogenic additives as antibiotic alternatives for Campylobacter, only a few have been thoroughly studied.
Inconsistent results emphasize the need for further research to understand their potential in poultry diets.Cinnamon, from the genus Cinnamomum (Lauraceae family), comprises over 250-300 aromatic evergreen shrubs and plant trees.However, only a few of these species hold substantial economic importance as a widely used spice globally (Ali et al., 2021).Cinnamon is rich in bioactive compounds, including volatile oils, flavonoids, curcuminoids, coumarins, tannins, alkaloids, xanthones, terpenoids, phenolics and more.These components contribute to its natural antioxidant, antimicrobial and anti-inflammatory properties (Liyanage et al., 2021;Ribeiro-Santos et al., 2017).Rosemary (Rosmarinus officinalis) is recognized for its medical benefits and aromatic properties, making it popular for various applications (Belenli et al., 2015).As a natural animal feed additive, its antimicrobial activity and antioxidant properties play a significant role (Abd El-Latif et al., 2013).These properties are attributed to the presence of bioactive compounds, including 1,8-cineole, rosemarinic acid and rosmarole, making it a valuable source of antioxidative compounds (Abd El-Latif et al., 2013;Franciosini et al., 2016;Jiang et al., 2011).Oregano (Origanum vulgare L.) is a highly aromatic herb with abundant active chemical compounds (Park et al., 2015).Oregano essential oil contains major components such as carvacrol and thymol, terpenoid compounds with antimicrobial properties (Teixeira et al., 2013).The polyphenols in oregano have also been studied for their antimicrobial activity and molecular mechanisms in suppressing microbes (Xu et al., 2008).Additionally, oregano extract serves as a natural antioxidant, effectively preventing lipid oxidation and contributing to improved meat quality and animal health (Lee et al., 2004).
Several studies have reported that these medicinal plants positively influence the performance, intestinal morphology, nutrient digestibility and gut microbiota of poultry (Abd El-Latif et al., 2013;Ashayerizadeh et al., 2009;Belenli et al., 2015;Franciosini et al., 2016;Mathlouthi et al., 2012;Ri et al., 2017;Saki et al., 2012).For example, the results of a study demonstrated that supplementing cinnamon led to significant improvements in body weight gain (BWG) and feed conversion ratio (FCR) in broilers, comparable to the group fed with oxytetracycline antibiotic (Singh et al., 2014).Moreover, Kanani et al. (2016) reported that including of 0.5% cinnamon in the feed significantly increased both feed intake (FI) and BWG compared to the control birds.Moreover, the use of rosemary in broiler chickens diets increased average daily gain, feed efficiency and European production efficiency factor (Petricevic et al., 2018).In another study, Ri et al. (2017) reported that the oregano supplementation increased broiler chickens' daily gain and daily FI during the grower period and the whole period.
Indeed, most of the previous research has primarily focused on investigating the effects of medicinal plants on poultry with normal health conditions.Therefore, this study sought to explore how cinnamon, rosemary and oregano powder affect broiler chickens challenged with C. jejuni regarding growth performance, excreta microbiota, intestinal morphology and nutrient digestibility.

Experimental design and diets
A total of 192 1-day-old male broiler chicks (Ross 308) were sourced from a commercial hatchery.Using a completely randomized design, the chicks were weighed and randomly assigned to 24 pens with 6 treatments and 4 replicate groups of 8 birds each.The trial began at 32

Growth performance and digestibility
FI was calculated as the difference between the offered and refused feed during the starter (0-21 days) and the grower (22-42 days).BWG was recorded, and FCR was determined as FI divided by BWG.
Moreover, the growth efficiency parameters, including the energy efficiency ratio (EER) and protein efficiency ratio (PER), were computed using the following formulas (Mir et al., 2018): EER = [Weight gain (g)/metabolizable energy intake (kcal)] × 100 PER = Weight gain (g)/crude protein intake (g) To assess dry matter (DM) digestibility, all diets contained 3 g/kg of chromium oxide (Cr 2 O 3 ), an inert marker, from days 39 to 42 of age.On day 42 of age, fresh excreta samples were collected from each pen to determine apparent DM digestibility.DM content of diets and excreta were determined using the method outlined in AOAC (2005).Excreta samples were stored at −20 • C until analysis.Subsequently, chromium was determined based on the method proposed by Shi et al. (2022).In summary, the samples were ashed in a muffle furnace at 600

Ileal morphology
Histomorphology study involved selecting two birds with body weights close to the average weight of each pen's replicate and slaughtering them by cervical dislocation at the trial's end.Ileal tissue samples were fixed in 10% neutral buffered formalin for 24 h, followed by dehydration, clearing and paraffin embedding.Five-micrometre sections were cut using a rotary microtome, mounted on glass slides and stained with alcian blue, periodic acid Schiff, haematoxylin and eosin.The villus height (VH) was defined as the distance from the villus tip above the lamina propria, whereas the villus width (VW) was measured at the basal and apical ends, and the mean widths were calculated.The villous surface area (VSA) and VH to crypt depth (CD) ratio were calculated according to Baurhoo et al. (2011).All measurements were conducted using a computer-aided light microscope image analysis.

Excreta microbiology
At 42 days of age, fresh excreta samples were collected and taken to the microbial lab on ice.According to Serpunja and Kim (2019),

Blood profile, atherogenic indices and liver enzyme activities
At the end of the experiment, blood samples from four birds in each treatment were collected in non-heparinised tubes from individual birds followed by serum harvesting and storage at −20 • C until analysis.

Statistical analysis
Statistical analyses were performed using the SAS software package (SAS Institute Inc., 2010).The pen was the experimental unit, and a completely randomized design with the GLM procedure was employed.
The Kolmogorov-Smirnov and Levene tests were used to test normality and variances.Tukey's multiple tests compared significant differences (p ≤ 0.05).

Ileal morphology
Table 3 shows the influence of dietary treatments on the ileal mor- It is important to highlight that the cinnamon-containing treatment displayed relatively less effectiveness compared to other additives, as cinnamon solely enhanced the VH to CD ratio in comparison to the PC group.

Excreta microbiota
The effects of different dietary treatments on the excreta microbiota of broilers are presented in

Blood profile, atherogenic indices and liver enzyme activities
The effects of dietary treatments on the blood profile and atherogenic indices and liver enzyme activities of broilers are presented in Table 5.The results showed that C. jejuni challenge has no effect on the plasma concentration of glucose, triglyceride, HDL, LDL and total cholesterol in the PC group (p > 0.05).Moreover, the concentration of glucose, triglyceride, HDL and LDL was not affected by the treatments containing additives (p > 0.05).Although in terms of total cholesterol concentration, no difference was observed between the TA B L E 5 Effects of dietary treatments on blood biochemistry (mg/dL) and atherogenic indices in broiler chickens challenged with Campylobacter jejuni.The impacts of various dietary treatments on the liver enzyme activities of broilers are outlined in Table 6.The administered treatments did not yield significant changes in AST, ALP and LDH levels (p > 0.05).

NC
The challenge with C. jejuni led to an elevation in ALT levels within the PC group (p < 0.05).However, diets containing rosemary, oregano, Erythromycin and, to some extent, cinnamon effectively averted the rise in ALT, demonstrating a response similar to that of the NC group (p < 0.05).

DISCUSSION
The results highlight several noteworthy findings that contribute to our understanding of the complex interactions between dietary treat- According to reports, antibiotics are known to enhance animal growth by altering bacterial metabolism (Ghunaim, 2009).Furthermore, exposure to antibiotics creates selective pressure within the digestive systems of animals, reducing the growth and spread of harmful bacterial strains such as Salmonella and Campylobacter (Ghunaim, 2009).As a result, the observed performance enhancement in the Erythromycin-fed group can be attributed to alterations in pathogen metabolism and reduced colonization.The FCR, representing the relationship between FI and weight gain, became more pronounced due to the decrease in growth rate induced by C. jejuni challenge in broilers.
As the challenge primarily impacted growth rate without affecting FI, the resulting increase in FCR within the C. jejuni-infected group (PC) is readily apparent.Aligning with the present findings, existing literature highlights that broiler challenge with C. jejuni elevates the FCR (Gharib Naseri et al., 2012).However, this unfavourable effect can be mitigated through the incorporation of dietary supplements such as organic acids, probiotics and medicinal plants (Gharib Naseri et al., 2012).
Given that thymol and carvacrol are the principal and most potent constituents of oregano essential oil (Kırkpınar et al., 2011), and these two compounds are attributed to oregano's antimicrobial activity (Mathlouthi et al., 2012), the enhanced performance observed in the oregano-fed group can be linked to the antimicrobial effects, leading to a reduction in Campylobacter colonization.This reduction subsequently curtailed bacterial toxin production, facilitated the restoration of nearnormal intestinal villi growth and improved nutrient digestion, like the characteristics observed in the NC group.
Verbenone, 1,8-cineole, camphor and borneol have been identified as the key compounds responsible for the antimicrobial properties of rosemary essential oil (Mathlouthi et al., 2012).Consequently, the improved performance observed in the rosemary-fed group can be attributed to the reduction in Campylobacter colonization.Furthermore, a separate study attributed enhanced growth performance in chickens fed with rosemary leaves to increased apparent dietary protein digestibility, along with improved nutrient availability in the intestines for efficient absorption, leading to accelerated growth (Botsoglou et al., 2007).This highlights yet another contributing factor to the improved performance of chickens receiving rosemary supplementation.
The inclusion of cinnamaldehyde in broiler diets has been cited as a promoter of growth performance attributed to its antimicrobial influence against detrimental bacteria and its enhancement of digestibility (Mehdipour et al., 2013).In our current experiment, the incorporation of cinnamon powder demonstrated performance improvement; however, this effect stood between the outcomes of the PC and NC treatments.In the current study, the utilization of Erythromycin, despite its effectiveness in diminishing Campylobacter colonization, coincided with a reduction in Lactobacilli counts.This phenomenon can potentially be attributed to the broad-spectrum nature of the mentioned antibiotic.

The reduction in
Beyond its impact on the reduction of gram-negative bacteria colonization, it also affects the population of gram-positive bacteria.In contrast, the utilization of phytogenic additives in this study ameliorated the decrease in Lactobacillus counts caused by the Campylobacter challenge, aligning their numbers more closely with those of the NC group.This beneficial effect of phytogenic additives could be attributed to their antibacterial properties against Campylobacter colonization.By curtailing the proliferation of Campylobacter, these compounds facilitate the establishment of a more balanced and stable intestinal microbial population, thereby mitigating the adverse consequences of the challenge.
In accordance with the findings of this study, previous research has indicated that incorporating antibiotics into broiler diets enhances growth performance while also leading to an increase in VH and VW and a decrease in CD (Marković et al., 2009).Phytogenic compounds, on the other hand, have been demonstrated to boost mucus production in the stomach and jejunum, signifying their protective role against gastrointestinal pathogens (Manzanilla et al., 2004).Further supporting these observations, the addition of a combination of thymol and carvacrol at 100 and 200 mg/kg, respectively, to broiler diets has been reported to elevate VH in the jejunum, although it showed no impact on VW (Hashemipour et al., 2013).The observed enhancement in intestinal morphology facilitated by the medicinal plants employed in this study can be attributed to their antibacterial compounds.By curbing Campylobacter colonization and preventing the decline in Lactobacilli count, these compounds contribute to optimal bacterial toxin concentrations.Consequently, they prevent villus damage and excessive CD, thus averting abnormal villus remodelling.
Plant essential oils serve as beneficial additives that enhance nutrient digestibility by elevating the activity of digestive enzymes and promoting the secretion of gastric and pancreatic juices.Their inherent antimicrobial properties contribute to the preservation of intestinal microvilli, consequently bolstering nutrients absorption.This effect is associated with an overall enhancement in digestibility coefficients (Fascina et al., 2012;Hernandez et al., 2004).Notably, an additional study underscores that the improved digestion and absorption in poultry's digestive systems when utilizing medicinal plants is attributed to the impact of their active components on the secretion of digestive enzymes such as proteases, lipase and amylase, coupled with the augmentation of intestinal villi count (Ponte et al., 2008).In this particular experiment, there was not a notable difference observed between the The assessment of poultry health relies heavily on analysing serum enzyme activities.Enzymes like ALT and AST, found predominantly in the liver, serve as specific indicators of hepatic cellular damage and inflammation (Selim et al., 2021).LDH isoenzymes, existing in various bird tissues, including liver, muscle, kidney and blood cells, decrease notably during liver diseases (Viveros et al., 2002).ALP, produced in all tissue types, aids in dephosphorylation and functions optimally in alkaline conditions (Selim et al., 2021).The findings from our study revealed that C. jejuni resulted in elevated serum ALT levels, suggesting a potential link to increased tissue damage and the disruption of liver functions.This connection is supported by previous reports associating higher levels of these markers with liver damage and inflammation (Selim et al., 2021;Viveros et al., 2002).Our findings align with reports stating that carvacrol usage inhibits blood biochemical changes induced by acrylamide, such as heightened ALT enzyme concentrations, consequently reducing liver damage (Cerrah et al., 2023).Additionally, thymol administration has been noted to alleviate liver damage characterized by decreased ALT levels (Dou et al., 2022).The observed reduction in ALT due to the medicinal plants used in this study can be credited to their antioxidant, antimicrobial and anti-inflammatory properties (Geyikoglu et al., 2019).

CONCLUSIONS
The findings from this study lead to the conclusion that both oregano and rosemary can mitigate the pathogenic impact of C. jejuni.These additives offer a viable alternative to Erythromycin in broiler feeding strategies.Nonetheless, employing higher concentrations is recommended if cinnamon is chosen for more robust outcomes.However, further experimentation is necessary to determine optimal cinnamon for achieving desired effects.
phology of broiler chickens exposed to C. jejuni challenge.The broilers fed with the PC diet demonstrated a decrease (p < 0.05) in VH, VH to CD ratio and VSA, yet displayed no adverse impact on VW and CD (p > 0.05).Incorporating additives mitigated this detrimental impact on ileal morphology, mirroring the results seen in the NC group (p < 0.05).
ments and C. jejuni challenge in broiler chickens' production.The results revealed that the introduction of a C. jejuni challenge had a detrimental effect on birds' performance, leading to reduced BWG and elevated FCR.These findings corroborate existing literature that establishes the negative impact of Campylobacter colonization on broiler growth and efficiency (Guyard-Nicodème et al., 2016).Importantly, treatments containing additives displayed a promising ability to mitigate the adverse effects of the Campylobacter challenge, resulting in performance resembling that of the NC group.These results emphasize the potential of medicinal plants in supporting broiler performance under pathogenic stressors.Notably, although the cinnamon-supplemented treatment exhibited relatively lower efficacy compared to other additives, it still demonstrated potential in alleviating the impact of Campylobacter challenge.
Lactobacilli count within the PC group following the C. jejuni challenge could potentially be attributed to increased Campylobacter colonization in the digestive tract.This surge in Campylobacter colonization might lead to competitive inhibition, subsequently diminishing the presence of beneficial bacteria like Lactobacilli, thereby contributing to dysbiosis in the bird's gut.Notably, several Clostridium perfringens species have shown sensitivity to carvacrol, cinnamaldehyde, citral and thymol.Utilizing these compounds is considered an effective strategy for managing the colonization of pathogenic bacteria and preserving intestinal health (Ouwehand et al., 2010).
treatments concerning excreta DM and DM digestibility, contrary to what was mentioned in other cases.One potential reason for this disparity could be attributed to the type and quantity of herbal additives utilized in this research.Biochemical parameters in the blood reflect the state of body organs influenced by various internal and external factors.According to the findings of this study, as well as research conducted byLee et al. (2004) andBampidis et al. (2005), which involved the inclusion of carvacrol, thymol and cinnamaldehyde in the diet of broilers, and oregano along with a commercial product containing essential oils in the diet of turkeys, it was revealed that these potent plant substances could potentially have positive effects on reducing blood cholesterol levels.This effect might occur through the inhibition of the activity of the regulatory enzyme responsible for cholesterol production, namely 3-hydroxy 3-methylglutaryl coenzyme A reductase.Additional research conducted byShamlo et al. (2014) demonstrated that incorporating medicinal plants like oregano into the diet of broilers stimulates the proliferation of beneficial bacteria such as Lactobacillus and Bifidobacterium within the intestine.This proliferation contributes to a reduction in blood cholesterol levels.These specific bacteria disrupt the intestinal-hepatic cycle of bile acids through consequently diminishing cholesterol absorption by reducing micelle formation.Traesel et al. (2011) supported our findings by indicating that using levels of 50, 100 and 150 mg/kg of a blend of oregano and rosemary essential oils in broiler diets did not affect HDL, triglyceride levels, total protein, albumin, globulin and the albumin-to-globulin ratio.However, in contrast to the outcomes of the current study, the same researchers reported that incorporating oregano and rosemary essential oils in the diet of broiler chickens did not significantly impact serum cholesterol levels.This discrepancy might be attributed to the relatively low levels of essential oils used in their research.Additionally, due to the volatile nature of essential oils leading to rapid evaporation, it might be necessary to prepare rations containing essential oils at least every other day to minimize evaporation and potentially observe their positive effects.The calculation formulas for atherogenic indices indicate that lower values are indicative of hypocholesterolemic and hypolipidemic effects.Although treatments containing herbal additives did exhibit a reduction in atherogenic indices to some degree, their overall impact was not considered significant.The experimental treatments notably influenced total cholesterol levels but did not sufficiently impact the other components within the atherogenic indices formulas, thereby resulting in minimal alteration of these indicators.

Table 2
Effects of dietary treatments on growth performance and dry matter digestibility in broiler chickens challenged with Campylobacter jejuni.Effects of dietary treatments on ileal morphology of broiler chickens challenged with Campylobacter jejuni.Means within a row sharing a common superscripts (a-c) are not different (p > 0.05).Abbreviations: CD, crypt depth; NC, negative control, basal diet without additive and without of C. jejuni challenge; PC, positive control, basal diet without additives but challenged with C. jejuni; VH, villus height (μm); VSA, villus surface area (mm 2 ); VW, villus width (μm).Effects of dietary treatments on broiler chickens' excreta microbial shedding challenged with Campylobacter jejuni (log 10 CFU/g).
illustrates the impact of dietary treatments on the growth performance and DM digestibility of broiler chickens exposed to C. jejuni challenge.The introduction of the C. jejuni challenge in the PC group negatively affected bird performance, leading to decreased BWG, EER and PER, along with an increase in FCR (p < 0.05).The inclusion of rosemary, oregano and Erythromycin alleviated this decline in performance (p < 0.05), resembling the outcomes observed in the NC group.Regarding BWG, EER, PER and FCR, it is worth noting that the treatment with cinnamon showed comparatively less effectiveness than the other TA B L E 2 Note: Means within a row sharing a common superscript (a, b) are not different (p > 0.05).Abbreviations: BWG, body weight gain (g); DM, dry matter (%); DM dig , dry matter digestibility (%); EER, metabolisable energy efficiency ratio (%); FCR, feed conversion ratio (g/g); FI, feed intake (g); NC, negative control, basal diet without additive and without of C. jejuni challenge; PC, positive control, basal diet without additives but challenged with C. jejuni; PER, protein efficiency ratio (g/g); SGR, specific growth rate (% per day).TA B L E 3Note: Means within a row sharing a common superscripts (a-c) are not different (p > 0.05).Abbreviations: NC, negative control, basal diet without additive and without of C. jejuni challenge; PC, positive control, basal diet without additives but challenged with C. jejuni.additives.This indicates that although cinnamon improved growth performance parameters, there was no significant difference compared to the NC and PC groups.Additionally, there were no significant differences in FI, excreta DM and DM digestibility among the experimental treatments (p > 0.05).C. jejuni-challenged broilers (PC group) exhibited lower values for excreta DM and DM digestibility compared to the other treatment groups.

Table 4
. The experimental treatments did not significantly influence the total counts of aerobic bacteria, Salmonella and Bifidobacteria (p > 0.05).However, the introduction of C. jejuni challenge increased Campylobacter colonization in birds fed with the PC diet.Remarkably, all treatments incorporating additives exhibited reduced Campylobacter colonization compared to the PC group (p < 0.05).Regarding Lactobacilli counts, the C. jejuni challenge resulted in a decline in Lactobacilli colonization within the PC group.Consequently, this group exhibited lower Lactobacilli count than the NC group and others (p < 0.05).Nonetheless, treatments incorporating rosemary, oregano and, to a certain extent, cinnamon were effective in preventing the reduction in Lactobacilli counts, showcasing effect akin to the NC group (p < 0.05).This protective effect, however, was not observed in the group receiving Erythromycin (p > 0.05).
Means within a row sharing common superscripts (a-c) are not different (p > 0.05).Abbreviations: AC, atherogenic coefficient; AI, atherogenic index; CRR, cardiac risk ratio; HDL, high-density lipoprotein; LDL, low-density lipoprotein; NC, negative control, basal diet without additive and without of C. jejuni challenge; PC, positive control, basal diet without additives but challenged with C. jejuni.Effects of dietary treatments on liver enzyme activities (U/L) in broiler chickens challenged with Campylobacter jejuni.
Note: Means within a row sharing common superscripts (a-c) are not different (p > 0.05).Abbreviations: NC, negative control, basal diet without additive and without of C. jejuni challenge; PC, positive control, basal diet without additives but challenged with C. jejuni; AST, aspartate aminotransferase; ALT, alanine aminotransferase; ALP, alkaline phosphatase; LDH, lactate dehydrogenase.treatments containing additives and the NC group; however, rosemary and oregano supplementation led to a decrease in its plasma concentration compared to the PC group (p < 0.05).Moreover, none of the plasma atherogenic indices, including CRR, AC and AI, were affected by bacterial challenge or feed additives (p < 0.05).